The development of new and improved methods for the treatment of cancer and palliation of the symptoms associated with cancer is of huge importance.
Common cancer therapies include the use of chemotherapeutic agents which are delivered systemically and have little or no tumour specificity, which results in the potential for harm to healthy organs in the body and causes symptoms such as myelosuppression, mucositis and alopecia.
Various forms of radiation are toxic to mammalian cells and have been harnessed successfully for the treatment of cancer. Radioactive isotopes have been used to treat certain cancers, for example cancers of the thyroid and prostate. Such therapies have also been employed for the treatment of disorders such as polycythemia vera. However, for logistical reasons including the considerable expense of suitable radiation delivery systems, radiation therapy is used less frequently than would otherwise be desirable.
Fractionation (and hypofractionation) methods have also been used in the treatment of cancer. These methods increase the likelihood of tumour cells being targeted during a phase of the cell cycle in which they are susceptible to radiation, rather than employing a single “dose” of radiation which may only interact with tumour cells at a phase of the cell cycle where the target cells are relatively resistant to radiation. Optimizing the potency of such techniques is the subject of much discussion in the field (see e.g. Yarnold, J., Bentzen, S. M., Coles, C., Haviland, J., Int. J. Radiat. Oncol. Biol. Phys., 2011, 79(1), 1). Brachytherapy techniques, such as the implantation into a tumour of solid radioactive “seeds”, which ensure a continuous source of radiation, have been used successfully in the treatment of prostate cancer (see e.g. Taira, A. V., Merrick, G. S., Butler, W. M., Galbreath, R. W., Lief, J., Adamovich, E., and Wallner, K. E., Int. J. Rad. Oncol., 2011, 79, 1336). However, the delivery of solid “seeds” into the appropriate area requiring treatment can be problematic.
Another established method in the field of oncology is embolization, i.e. the occlusion of blood vessels within a tumour to bring about a therapeutic benefit. Artificial emboli such as platinum coils or inflatable balloons are common. Furthermore, liquid embolic agents have been developed, including n-butyl-2-cyanoacrylate (Enbucrilate), which polymerizes upon contact with moisture, blood and/or tissue forming a glue to obstruct blood vessels.
However, there remains a need for further minimally invasive methods by which a wide range of tumours or other lesions may be targeted in a selective, predictable and efficient manner in order to achieve palliation of symptoms or destruction of all or part of the mass of a tumour or other lesion. This includes a need for improved ways of harnessing radioactive isotopes for use in such therapies.